Self-described artist, maker, and teacher Markus Opitz has built an ultra-compact portable camera — designed to save energy by only firing up its Espressif ESP32-S3 microcontroller when you actually press the button to take a photo.
"Amazingly tiny outdoor photo cam for quick one-handed use," Opitz writes of his creation. "This camera is lightweight (26g), cheap and can be operated with just one hand. It is for photos only, not for videos! [You] hold the device steady and keep the button pressed. During image capture and storage the LED is on. Keep button pressed until the LED goes out again (-3 sec), then the saving process is complete."
The heart of the project, hidden away inside a 3D-printed housing which looks like a pocket camera that shrunk in the wash, is a Seeed Studio XIAO ESP32-S3 Sense — built around the Espressif ESP32-S3 microcontroller and boasting integrated battery management and an on-board Ominvision OV2640 camera module. While it also includes 2.4GHz Wi-Fi and Bluetooth 5 Low Energy (BLE) connectivity, they're not in use in Opitz's project.
Opitz's approach to maximizing battery life is simple indeed: the camera's shutter button is actually wired between the microcontroller and the project's lithium-polymer battery. By holding it down, the microcontroller is powered and booted — at which point it lights an LED and captures an image, writing it to a microSD Card loaded into its on-board reader. When the LED goes out, the writing has finished and you can release the button.
It's a brute-force method of power management which ensures absolutely zero "vampiric" drain from the battery while the camera isn't in use — but that comes at a cost: if you let go of the shutter button before the LED goes out, your photo will almost certainly be corrupted.
"In several tests I could make about 120 pictures (720×420 px) with one battery charge," Opitz says of the camera's performance. "It is as exciting as it used to be in the good old pre-digital age: you didn't have a display then and you had to wait until the pictures were developed. Yes, and some pictures are not […] good either — like in the past!"
The full project write-up is available on Opitz's Instructables page.